import { cloneDeep as deepClone } from '@/utils/methods'

const componentChild = {}
/**
 * 将./slots中的文件挂载到对象componentChild上
 * 文件名为key，对应JSON配置中的__config__.tag
 * 文件内容为value，解析JSON配置中的__slot__
 */
const slotsFiles = require.context('./slots', false, /\.js$/)
const keys = slotsFiles.keys() || []
keys.forEach(key => {
    const tag = key.replace(/^\.\/(.*)\.\w+$/, '$1')
    const value = slotsFiles(key).default
    componentChild[tag] = value
})

function vModel(dataObject, defaultValue) {
    dataObject.props.value = defaultValue

    dataObject.on.input = val => {
        this.$emit('input', val)
    }
}

function mountSlotFiles(h, confClone, children) {
    const childObjs = componentChild[confClone.__config__.tag]
    if (childObjs) {
        Object.keys(childObjs).forEach(key => {
            const childFunc = childObjs[key]
            if (confClone.__slot__ && confClone.__slot__[key]) {
                children.push(childFunc(h, confClone, key))
            }
        })
    }
}

function emitEvents(confClone) {
    ;['on', 'nativeOn'].forEach(attr => {
        const eventKeyList = Object.keys(confClone[attr] || {})
        eventKeyList.forEach(key => {
            const val = confClone[attr][key]
            if (typeof val === 'string') {
                confClone[attr][key] = event => this.$emit(val, event)
            }
        })
    })
}

function buildDataObject(confClone, dataObject) {
    Object.keys(confClone).forEach(key => {
        const val = confClone[key]
        if (key === '__vModel__') {
            dataObject.attrs[key] = val
            vModel.call(this, dataObject, confClone.__config__.defaultValue)
        } else if (dataObject[key] !== undefined) {
            if (
                dataObject[key] === null ||
                dataObject[key] instanceof RegExp ||
                ['boolean', 'string', 'number', 'function'].includes(typeof dataObject[key])
            ) {
                dataObject[key] = val
            } else if (Array.isArray(dataObject[key])) {
                dataObject[key] = [...dataObject[key], ...val]
            } else {
                dataObject[key] = { ...dataObject[key], ...val }
            }
        } else {
            dataObject.attrs[key] = val
        }
    })

    // 清理属性
    clearAttrs(dataObject)
}

function clearAttrs(dataObject) {
    delete dataObject.attrs.__config__
    delete dataObject.attrs.__slot__
    delete dataObject.attrs.__methods__
}

function makeDataObject() {
    // 深入数据对象：
    // https://cn.vuejs.org/v2/guide/render-function.html#%E6%B7%B1%E5%85%A5%E6%95%B0%E6%8D%AE%E5%AF%B9%E8%B1%A1
    return {
        class: {},
        attrs: {},
        props: {},
        domProps: {},
        nativeOn: {},
        on: {},
        style: {},
        directives: [],
        scopedSlots: {},
        slot: null,
        key: null,
        ref: null,
        refInFor: true,
    }
}

export default {
    props: {
        conf: {
            type: Object,
            required: true,
        },
    },
    render(h) {
        const dataObject = makeDataObject()
        const confClone = deepClone(this.conf)
        const children = this.$slots.default || []

        // 如果slots文件夹存在与当前tag同名的文件，则执行文件中的代码
        mountSlotFiles.call(this, h, confClone, children)

        // 将字符串类型的事件，发送为消息
        emitEvents.call(this, confClone)

        // 将json表单配置转化为vue render可以识别的 “数据对象（dataObject）”
        buildDataObject.call(this, confClone, dataObject)

        return h(this.conf.__config__.tag, dataObject, children)
    },
}
